Art of concentrating magnetic iron ores



(No Model.)

G. Q ONKLING.

ART OF GONGENTRATING MAGNETIG IRON OBE- No. 504,200. Patented Aug.29,1893.

WITNESSES-I I I /NVE)VTOH: garden flmklz'vy fiTJKMc-WM BY NITE TATESATENT OFFICE.

GURDON CONKLING, OF GLENS FALLS, NEW YORK.

ART OF CONCENTRATING MAGNETIC lRON ORES.

SPECIFICATION forming part of Letters Patent No. 504,200, dated August29, 1893.

Application filed September so, 1891. SerialNo.407,289. (No specimens.)

To all whom it may concern:

Be it known that I, GURDON CONKLING, a citizen of theUnited States,residing at Glens Falls, in the county of Warren and State of New York,have invented new and useful Irn provements in the Art'of ConcentratingMagnetic Iron Ores, of which the following is a specification.

Myinvention relates to that method of concentration in which magneticattraction is employed as the agency for separating the iron from thegangue and the object of my improve? ment is the attainment of a highdegree of purityin the concentrated product in an economical manner.

The apparatus which may be used in carrying out my invention isillustrated in the accompanying drawings in which- Figure 1 represents alongitudinal vertical section of a magnetic separator to be used whenthe crushed ore is in a wet state. Fig. 2 is a plan or top View of amagnetic separator to be used when the mass to be concentrated is in adry state.

Two general methods of concentration have heretofore been employed intreating magnetic iron ores in one of which, known as the wet process,the ore is crushed and then concentrated in a wet state, while in theother, known as the dry process, the ore is crushed in a dry state andthen concentrated while dry. By neither of these processes is itpossible to obtain a substantially pure product containing say fromseventy to seventy-two per cent. of metallic iron without a wastefulloss of ore. I

In the crushing to which the ore has to be subjected to prepare it forconcentration, a part of the rock or gangue is broken into smallparticles while a considerable proportion of it is reduced to a finepowder or dust.

In the process of concentrating the ore in the wet state while thegangue dust is washed away, the small particles of gangue tend to clingto the particles of ore and in order to remove such particles of gangue,the ore mnstbe subjected to so many repeated washings andconcentrations, that a large quantity of ore will be carried away withthe gangue, so that while a concentrate containing say from fifty tosixty per cent. of metallic iron may be profit ably obtained by this wetprocess, such process cannot be carried much beyond this point withouttoo wasteful loss of ore; it cannot therefore be profitably employed tobring magnetic iron ores containing phosphorus within the Bessemer steellimits.

An additional disadvantage of the wet process is found in the fact thatin cold weather or in cold climates the wet concentrate when placed on acar or vehicle for transportation is liable to freeze into a solid massand in this state it is refused by the furnace man. In the dry process,on the other hand, an almost prohibitory item of expense is found in thewear and tear of belts and machinery and injury to the health ofoperatives caused by the great quantity of floating dust due to thecrushing, screening and concentrating of the mass in the dry state andat the same time a very considerable percentage of iron in the shape ofexcessively fine particles is carried away with the gangue dust into thedust collectors. When applied to ores containing iron pyrites orsulphuret of iron, the dry process is inadequate to the production of asubstantially pure concentrate, since the degree of heat necessarilyapplied for drying, the mass volatilizes a portion of the containedsulphur and thus renders the sulphuret magnetic, so that it is taken outby the magnets with the iron and remains in the concentrate as animpurity.

By means of my invention I obviate the disadvantage incident to both thewet and the dry .process and am enabled to obtain a substantially pureconcentrate containing from seventy to seventy-two per cent. of metalliciron without any material loss of ore.

To this end my invention consists in first comminuting the ore in thepresence of water, then exposing the comminutedore while being carriedin a stream of water to the action of magnets and continuously removingthe magnetic particles which have been attracted by the magnets from themagnetic field, while the non-magnetic particles are carried away by thewater, then drying the magnetic particles and exposing the driedparticles to the action of magnets.

In carrying my invention into efiect, I first crush the ore in a damp orwet state, which may be done as the ore comes from the mine or from thedump or waste pile, to such asize as may be most desirable according tothe nature of the ore to economically break apart the particles of ironand rock or gangue. The crushed mass 'is then concentrated by means ofmagnets in the presence of a suffieient quantity of water to wash theore thoroughly and as far as practicable float apart and separate theparticles of ore from those of rock or gangue and other waste matter. Iprefer to apply the water in the shape of a running stream caused topass over and through the mass while the same is being subjected to themagnetic attraction. This concentration should be continued only so faras it may be done without removing any mate rial proportion of the orewith the gangue. By this means all the fine non-magnetic dust and alarge proportion of the small particles of non-magnetic matter will beremoved from the mass which will be reduced in bulk from fifty toseventy-five per cent. Substantially all the magnetic materialoriginally present in the crushed mass will be found in the concentratewhich will contain from fifty to sixty per cent. of metallic ironentirely free from gangue dust. In carrying out this part of my process,I may use with advantage such an apparatus as is shown in Fig. 1 of thedrawings, in which A designates an endless belt which extends overrollers -B B and is placed in an inclined position. F is a magnet whichis situated in the interior of the belt close to its upper branch. E isa trough over which the crushed ore, mixed with water, is fed to thebelt A and S is a spray pipe for washing the particles of ore which areattracted by the magnets. The belt A moves in the direction of arrow 1and the particles which are attracted by the magnet are carried by thebelt over the pulley B and they are collected in the receiver L. Theparticles which are not attracted by the magnet, are carried by thestream of Water over the pulley B and are collected in the receiver K.The concentrate produced as above described will still contain aconsiderable percentage of small particles of nonmagnetic matter whichwill cling to the particles of ore while wet. In order to remove thesenonmagnetic particles, I next thoroughly dry the mass, thereby causingthe clinging particles of ore and rock to fall apart. This dryingoperation is greatly facilitated by the reduction in the bulk of themass effected by the preceding partial concentration and, furthermore,the drying can be efiected at such a low temperature, that in treatingores containing sulphurets of iron no sulphur is volatilized, thusleaving thesulphurets in their non-magnetic state. After the mass hasbeen dried, I complete the concentration by subjecting it while still inthe dry state to the action of magnets thereby separating froni the oresuch impurities as were left associated with it at the conclusion of thewet treatment.

Owing to the removal of the gangue dust, d uring the wet treatment verylittle if any dust is raised during the subsequent steps of drying andconcentrating, thus avoiding the difficulties incident thereto in thedry process.

In carrying the dry concentration into effect, I may use the apparatusshown in Fig. 2 of the drawingsin which A represents the main belt and Gthe secondary belt which extends at right angles over themain; belt A;and in the interior of which close to its lower branch are situated themagnets F.

The mass to be separated is fed to the main belt A through the hopper Eand the mag.- netic particles which are attracted by the magnets F arecarried away by the belt 0 in the direction of arrow 1, while the ganguewhich remains on thebelt A, is carried away in the direction of arrow 2.

It may be remarked as a matter of commercial advantage that it may attimes be economical to carry on the wet part of my process at the mineand then to transport the partially concentrated wet product to thefurnace and utilize the waste furnace heat for the drying required andprior to the completion of the process.

What I claim as new, and desire to secure by Letters Patent, is

The herein described process of concentrating magnetic iron ore whichconsists in first comminuting the ore in the presence of water, thenexposing the comminuted ore while being carried in a stream of Water tothe action of magnets and continuously removing the magnetic particleswhich have been attracted by the magnets from the magnetic field whilethe non-magnetic particles are carried away by the water, then dryingthe mag,- netic particles and finally exposing the dried particles tothe action of magnets.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

GURDON CONKLING. Witnesses:

WM. 0. HAUFF, E. F. KASTENHUBER.

